Electrical properties of polyetherimide thin films: Non-parametric dielectric response analysis with distribution of relaxation times
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High temperature polymeric materials for electrical insulation and energy storage are needed for transformational power applications such as pulsed-power and hybrid electrical vehicles. One of the candidate materials has been polyetherimide, an amorphous thermoplastic with a glass transition over 200 °C. Here, the dielectric studies on the material are reported by taking into account the polarization and conduction processes in the polyetherimide. The dielectric data were analyzed with the distribution of relaxation times approach with Debye expression as the kernel in the inversion algorithm, the results then created the relaxation map for polyetherimide. The method satisfies the Kramers-Kronig relationships, so the ohmic conductivity and permittivity at high frequencies could be estimated from the experimental data even if there exists significant measurement error. The data were compared to the published results on polyetherimide in the literature. The materials is a low loss polymer with negligible ohmic losses below 200 °C. The estimated fragility of the polyetherimide was high about 284 from the resolved relaxation map using the Vogel-Fulcher-Tammann-Hesse expression. Polyetherimide is a good dielectric for advanced energy storage and electrical insulation technologies up to 200 °C.